Electric switch



March 9, 1954 H. c. swAY 2,671,840

` ELECTRIC SWITCH Filed March 26, 1952 FLC/2 'InQentor Henry C. Swag,

His Attorjneg.

Patented Mar. 9, 1954 ELECTRIC SWITCH Henry C. Sway, Bridgeport, Conn.,assignor to General Electric Company, a corporation oi' New YorkApplication March 26, 1952, Serial No. 278,657

Claims.

This invention relates to electric switches, more particularly to suchswitches having a pair of coacting contact elements, and its principalobject is to provide such a switch wherein failure of the contacts toclose due to an accumulation of foreign matter on the surfaces of thecontacts, as dust or an oxide of the material of which the contacts aremade, is substantially eliminated.

More specifically, this invention has for an object the provision of animproved electric switch embodying improved contact structure and meansfor effecting a sliding or wiping motion between the contacts as theyopen and close so as to eiect a cleaning action and thereby prevent theaccumulation of foreign matter between them.

In accordance with my invention, I provide an elastic arm which carriesone of the switch contacts. This contact is mounted on a portion of thearm which is bowed with respect to the main body of the arm, as byangularly relating that portion to the main body, and it engages a xedcontact whose contact area is substantially parallel to the angledportion of the arm; and the bias of the arm holds the contacts inengagement. An actuating element engages the body of the arm to move itto effect separation of the contacts and to permit it to move to reclosethem. But its motion to open the contacts is resisted by a secondelastic member which engages the arm substantially at the juncture pointbetween the main body of the arm and its angularly deflected contactcarryingportion; and also is arranged to bias the contacts closed. Andits tension is such that the switch arm when operated to open, rst warpsabout the second elastic member as a fulcrum before the contacts open,thereby to wipe or slide its contact across the face of the othercontact, and only after this happens does the second elastic memberyield to permit the contacts to open. Moreover, the parts are soarranged that the contact pressure is actually increased by the actionof the second or pressure applying elastic member during the wipingstage of the opening operation. Likewise when the contacts close, theyclose with a wiping action.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawing and its scope will bepointed out in the appended claims.

In the drawing, Fig. l is a plan view of an electric switch embodyingthis invention; Fig. 2 is a vertical sectional view taken through theline 2 2 of Fig. 1 and looking in the direction of the arrows; Fig. 3 isa fragmentary sectional View similar to Fig. 2 illustrating the switchin its closed position and drawn to a larger scale than Figs. l and 2;Fig. 4 is a sectional View similar to Fig. 3 but illustrating the switchelements at one stage of the opening operation; and Fig. 5 is a (Cl.20D-164) View similar to Figs. 3 and 4 but illustrating the switchcontacts in their open position.

Referring to the drawing, this invention has been shown in one form asapplied to an electric switch comprising a base I formed as a flat platehaving parallel upper and lower flat surfaces; this plate may be formedof any suitable electrically insulating material such as a suitableelectrically insulating plastic. Mounted upon the plate I is a fixedcontact 2 formed of any suitable material such as silver, and in theshape of a rivet, and mounted in rivet-like fashion upon a supportingbracket 3; the bracket 3 is of angular shape, as shown, having a baseportion il and an upwardly extending contact supporting section 5arranged at an angle to the base 4 so that it supports the contact 2with its engaging face at an angle of substantially 45 to the topsurface of the base I. The base t has one end portion, the lower endportion, as viewed in Fig. 1 wrapped around that edge of the base I, andits other end 6 constitutes a terminal connection for the xed contact 2;the wrapped portion of base :l is inserted in a recess 5a provided inthe edge of plate I so that it is secured against turning with respectto the plate. The bracket 3 as a whole is riveted to the base I by meansof a rivet 1, and this rivet 1 also forms the terminal connection for anelectrical supply conductor 8 which it will be understood will beconnected in a suitable electrical circuit to be controlled.

Also mounted upon the base I to coact with the xed contact 2 is amovable contact 9 similar to the contact 2. The contact 9, however, ismounted upon an elastic switch arm II] which by its inherent resiliencytends to maintain the two contacts in closed position, as shown in Figs.2 and. 3. The contact arm I0 is in the form of a relatively elongatedstrip extending lengthwise across the top of the base I from thecontacts toward the left of the plate, as shown, where its left-hand endis anchored to the base I through the medium of a suitable terminalplate II; as shown, the left-hand end of the switch arm 1s connected tothe terminal plate II by means of a suitable rivet I2; the arm II) isprevented from rotating with respect to the terminal plate II by meansof a tongue I3 formed on and extending upwardly from the terminal plateand received in a slot I4 provided for it in the end of the contact arm.Here again the terminal plate may be connected to a suitable externalconductor I5 by means of a suitable rivet I6 which rivet also functionsto secure the terminal plate II to the base I and thereby also serves toconnect the switch arm I0 to the base I. This terminal plate like theterminal plate 6 also has one end, its lower end as viewed in Fig. 1,wrapped around the lower edge of the plate in a recess-I1 provided forin the plate so as to pre.

by said contact, means anchoring the other end of said arm so that itbiases said contacts together with a predetermined force, biasing meansapplying an elastic force to said arm substantially at the juncture ofsaid body and end portions to increase the pressure between saidcontacts, and an operating element for applying a force to said armintermediate its said other end and said juncture to open said contacts,said biasing means applying an elastic force of such magnitude thatinitially it resists movement of said arm away from said xed contactwhereby said arm flexes to effect relative shifting movement andincreased pressure between said contacts prior to their opening andthereafter yields to permit opening movement of said arm.

2. Switch structure comprising a base, a fixed contact on said basehaving a contact area in a plane at an acute angle to said base, anelastic switch arm lying over said base having an end remote from saidcontact fixed to said base and its other end portion adjacent saidcontact, said latter end portion being deected outwardly from the bodyof said arm to lie in a plane substantially parallel to said rst planeand having a contact area engageable with said xed contact area, theresiliency of said arm biasing said contacts together, a second elasticarm relatively unyielding as compared with the flrst having one endremote from said contact secured to said base and its other end engagingsaid first arm at the juncture thereof with its deiiected contact endportion and biasing said arm to increase said contact pressure, and anactuating member engageable with said rst arm at a point intermediateits fixed end and said juncture to move it away from and to permit it toreturn toward said base thereby to open and reclose said contacts, saidsecond elastic arm applying an elastic force of such magnitude thatinitially it resists movement of said rst arm away from said fixedcontact whereby said first arm exes to effect relative shifting movementand increased pressure between said contacts prior to their opening andthereafter yields to permit opening movement of said first arm.

3. Switch mechanism comprising a flat base, a fixed contact on said basehaving a contact area lying in a plane substantially 45 with said base,an elastic switch arm having one end fixed to said base extending fromsaid end across said base toward said xed contact where its other enddeflects outwardly from the base at an angle of substantially 45, saidlatter end carrying a contact area biased into engagement with saidfixed contact area by said elastic switch arm, a second elastic armrelatively unyielding as compared with the rst having one end remotefrom said contacts secured to said base and its other end engaging saidfirst arm at the juncture thereof with its deflected contact end portionand biasing said first arm to increase said contact pressure, and anactuating member engageable with said first arm at a point intermediateits fixed end and said juncture to move it away from and to permit it toreturn toward said base thereby to open and reclose said contact areas,said second elastic arm applying an elastic force of such magnitude thatinitially it resists movement of said first arm away from said fixedcontact area whereby said first arm exes to effect relative shiftingmovement and increased pressure between said contact areas prior totheir opening and thereafter yields to permit opening movement of saidflrst arm.

4. Switch structure comprising a base having a flat supporting surface,a fixed contact member on said surface having a contact area lying in aplane forming an acute angle with said surface, a pair of superimposedelastic arms on said base attached together and to said surface at oneend, the outer arm being relatively more rigid than the inner arm andboth biased toward said surface, and the outer arm curving outwardlyaway from the inner arm from their xed ends to a point adjacent theother end portion of the inner arm where it curves inwardly to engagesaid inner arm, said other end portion of said inner arm deflectingoutwardly at the point of engagement between said arms at an acute anglewith respect to said surface, which angle is substantially the same assaid first mentioned acute angle, a contact on said deflected endengageable with said fixed contact area, and an actuating memberengageable with said inner arm intermediate its fixed end and said pointof engagement to operate it to effect the opening and closing of saidcontacts, said outer arm applying an elastic force of such magnitudethat initially it resists movement of said inner arm away from said xedContact whereby said other end portion pivots about said point ofengagement to effect relative shifting movement and increased pressurebetween said contacts prior to their opening and thereafter yields topermit opening movement of said inner arm.

Switch structure comprising a base having a plane supporting surface, axed contact arm on said surface having a contact area lying in a planesubstantially 45 to said surface, an elastic switch arm relatively longas compared with its width extending lengthwise along said surface andhaving one end adjacent said fixed contact area deected outwardly at anangle to the body portion of said arm so as to be substantially parallelto said xed contact area and having a contact area engageable with saidxed area, means anchoring the other end of said arm to said surface toiiex said arm to bias said contact areas together with a predeterminedforce, a second elastic arm relatively more rigid than the rstsubstantially coextensive with the body portion of the flrst and spacedtherefrom substantially throughout its length but having one endengaging said first arm at the juncture between the body thereof and itsdeflected end portion, thereby to act as a fulcrum for said first arm,means anchoring the other end of said second arm to said base to causeit to engage said juncture with a predetermined force, and an actuatorengageable with said flrst arm at a point intermediate said juncture andits said other end to effect the opening and closing of said contacts,said second elastic arm applying a force of such magnitude thatinitially it resists movement of said rst arm away from said fixedcontact whereby said deflected end portion pivots about said juncture toeffect relative shifting movement and increased pressure between saidcontacts prior to their opening and thereafter yields to permit openingmovement of said flrst an HENRY C. SWAY.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,804,748 Derrick May 12, 1931 2,199,357 Dillman et al. Apr.30, 1940 2,507,381 Morse May 9, 1950

